K2 ≤ 2.24 contains a mass-assignment defect in the K2 system user plugin plguserk2. A Registered Joomla user, by including the field K2UserForm=1 in a standard comusers profile.save POST, can write arbitrary values into the notes, image, and plugins columns of their own row in the #k2users table — none of which are exposed by the K2 frontend profile-edit form.